It was 14:57 BST on 11 September 2008. A France-bound Eurotunnel Shuttle was halfway through its 50-kilometre run under the English Channel, carrying 27 heavy goods vehicles and 32 people, mostly lorry drivers riding with their trucks. One of the vehicles caught fire in the North Tunnel about 11 kilometres from the French portal at Coquelles. Eyewitnesses heard two loud bangs that they described as explosions before thick smoke poured through the carriage. The train stopped. The cabin went dark. The driver of one lorry later said the temperature very quickly became, in the careful phrasing of the official report, very hot. In a confined space 75 metres beneath the seabed, in pitch black, with smoke pouring in and an emergency exit jammed shut, someone took a hammer to a window and made his own way out.

The Channel Tunnel has a clever layout. Two main running tunnels carry trains in opposite directions, separated by a narrower central service tunnel that is kept at slight positive pressure so smoke cannot drift into it from the running bores. Cross-passages link the three. When the alarm sounded, all 32 people on board the burning shuttle were led across to the service tunnel and walked out to safety. Fourteen were treated in hospital for minor injuries, mostly smoke inhalation. No one died. That outcome was not luck. It was engineering, working exactly as designed even when one of the human details, that stuck emergency door, was failing. The service tunnel saved every life in it that afternoon.

Above ground, more than 300 firefighters from both sides of the Channel converged on the portals. Crews came from East Sussex, West Sussex, London, and Essex on the British side, and from across northern France. They could not get to the fire in time. Eurotunnel's procedure required ventilation to clear the smoke before evacuation, and the fans were left running. They also fed the fire. It took 75 minutes before crews began to tackle the blaze directly, and the strong ventilation made it bigger. There had been a worry that one of the lorries was carrying 100 kilograms of phenol, the toxic carbolic acid used in pharmaceuticals; on inspection it turned out to be 100 grams. The fire burned for 16 hours, reaching temperatures of about 1,000 degrees Celsius. It destroyed six wagons and a locomotive. About 650 metres of tunnel were damaged, 50 percent more than the November 1996 fire that had been the previous worst incident.

The undamaged south tunnel reopened first. A test freight train slipped through it at 00:08 BST on 13 September. Eurostar resumed limited passenger service at 06:00 the same morning, with 18 trains in each direction including the family-favourite London-to-Disneyland-Paris run. Some passengers reported smelling smoke at St Pancras at the end of their journey. By the end of September two-thirds of the north tunnel had been brought back into service. The final sixth, where the heat had attacked the concrete itself, took months to repair. Workers replaced over a thousand bolts holding the tunnel lining, blasted the damaged concrete away with high-pressure water jets, repaired the steel reinforcing mesh, then sprayed on 4,000 tonnes of new shotcrete to rebuild the lining from the inside out. Total repair cost: 60 million euros. Full service resumed in February 2009.

The investigation, led jointly by France's Land Transport Accident Investigation Bureau and Britain's Rail Accident Investigation Branch, published its report on 22 November 2010. The findings were sober. Evacuation instructions, previously in only English and French, would now be displayed in the lorry drivers' club car in nine languages. After tests in April 2010, Eurotunnel built four SAFE stations along the tunnel: places a burning train could limp to, where passengers and crew could be evacuated into the service tunnel while an automatic water-mist system put the fire out. The stations went operational in autumn 2011 and were live-tested in January 2012. The 2008 fire was the third the tunnel had survived since opening in 1994: 1996, 2006, and now 2008. Today every Channel Tunnel shuttle journey is shaped by what the 32 people in the North Tunnel learned that September afternoon, including the one who reached for the hammer.